Why is the shaft diameter of the multi-pole low-speed motor larger?

When a group of students visited the factory, they asked a question: Why are the diameters of the shaft extensions of two motors with basically the same shape obviously inconsistent? Regarding this aspect, some fans have also raised similar questions. Combined with the questions raised by fans, we have a simple exchange with you.

The diameter of the shaft extension is the key to the connection between the motor product and the driven equipment. The shaft extension diameter, keyway width, depth and symmetry all directly affect the final connection and transmission effect, and are also the key objects of the control of the shaft processing process. With the application of automated numerical control equipment in the parts processing link, the control of the shaft processing link has become relatively easy, and the focus has shifted to the size selection of the design link and how to constrain the relationship between the assessment elements of each part.

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Regardless of the general-purpose series or special-purpose series motors, the diameter of the shaft extension is related to the rated torque. There are very strict regulations in the technical conditions of the motor products. Failure of any one of the assessment elements will lead to the failure of the whole machine. As the basis for the selection of the matching motor for the customer’s equipment, it will also be clearly stated in the product catalog of each motor factory and consistent with the technical conditions; and for the shaft extension size different from the standard motor, it will be summarized as a non-standard shaft extension, and the customer has When such requirements are required, technical communication with the motor manufacturer is required.

Motor products transmit torque through the shaft extension. The diameter of the shaft extension must match the transmitted torque, and the size must ensure that the shaft extension does not deform or break during the operation of the motor.

Under the condition of the same center height, the diameter of the shaft extension is relatively fixed. Usually, the shaft extension diameter of a 2-pole high-speed motor is one gear smaller than that of other 4-pole and above low-speed motors. However, the diameter of the shaft extension of the small-power motor with the same frame is unique, because the size of the transmitted torque is not enough to affect the diameter of the shaft extension, there will be a qualitative difference, and the versatility is the dominant factor.

Taking the motor with the same center, high power, and different poles as an example, the rated torque of the motor with fewer poles and high speed is smaller, and the rated torque of the motor with more poles and low speed is larger. The size of the torque determines the diameter of the shaft, that is, the torque of the low-speed motor is relatively large, so it will correspond to a larger shaft diameter. Because the power spectrum covered by the same frame size may be relatively wide, sometimes the diameter of the shaft extension of the motor with the same speed also needs to be graded. In view of the general requirements of motor components with the same center and high number of poles, it is best to set different shaft extension diameters according to the number of motor poles under the condition of the same center height, so as to avoid further subdivision under the condition of the same pole and the same center height .

According to the difference in motor torque under the same center height, same power and different speed conditions, what the customer sees is only the difference in the diameter of the motor shaft extension, and the actual internal structure of the motor shell is even more different. The outer diameter of the rotor of a low-speed, multi-pole motor is larger, and the layout of the stator winding is also significantly different from that of a few-stage motor. Especially for 2 extremely high speed motors, not only the diameter of the shaft extension is one step smaller than that of other pole number motors, but also the outer diameter of the rotor is extremely small, the end of the stator occupies a large proportion of the inner cavity space of the motor, and there are many ways of electrical connection at the end. And many products with different performances can be derived through electrical connection.

In addition to the difference in the diameter of the motor shaft extension, there are also some differences in the shaft extension and rotor type of the motor for different purposes. For example, the shaft extension of the hoisting metallurgical motor is mostly a conical shaft extension, and some motors for driving and electric hoists require conical rotors. wait.

For electric motor products, in view of the basic requirements of serialization and generalization of components, the shape and size of components contain specific performance characteristics. How to truly understand and understand these size codes is really a relatively large technology. topic.


Post time: May-25-2023